Aluminum Knurled Thumb Screws 6#-32 × 20mm – Flat Head Set Screws in 10 Colors for DIY, Electronics & Panel Fastening

6#-32 is a UNC (Unified National Coarse) thread designation. The "6" refers to the screw gauge (approximately 3.5mm / 0.138" outer diameter) and "32" refers to 32 threads per inch. This is a common size used in electronics enclosures, PC cases, and DIY panel assemblies. The screw length is 20mm (approximately 25/32"), measured from the underside of the head to the tip. To confirm fit, check that your threaded insert or nut is also rated for 6-32 UNC.

Choose the 20mm length when your panel stack-up is thicker than typical single-panel enclosures — for example, when fastening through two layers of sheet metal, a panel plus a gasket, or a thicker plastic housing. The extra thread engagement compared to a 16mm screw also provides a more secure hold in softer materials like plastic or aluminum where thread stripping is a concern under repeated removal cycles.

Aluminum thumb screws are lighter and corrosion-resistant but have lower tensile strength than steel. They are designed for hand-tightening applications where tool torque is not applied — such as panel covers, access doors, electronics enclosures, and DIY project boxes. For structural or high-torque applications, steel screws are generally recommended. Aluminum thumb screws are well-suited for frequent removal and reinstallation under normal hand-use conditions.

Anodized aluminum has good corrosion resistance and can handle occasional outdoor exposure. For prolonged outdoor use in wet or coastal environments, stainless steel thumb screws are generally more durable. For indoor use, electronics enclosures, and protected outdoor panels, anodized aluminum thumb screws perform well without rusting or staining the surrounding material.

These screws use the 6#-32 UNC (Unified National Coarse) thread standard, which is an imperial thread. They are not compatible with metric nuts or inserts. Ensure your mating hardware (nut, threaded insert, or tapped hole) is also 6-32 UNC. Do not mix with M3 or other metric threads, as the pitch and outer diameter are different and cross-threading will damage both the screw and the mating part.

For a single project with a few access panels, the 1 or 5 pcs option is typically sufficient. For PC builds or electronics enclosures that use 4–8 thumb screws per unit, the 8 or 10 pcs option provides enough for one build with a few spares. For workshop stock, prototyping labs, or multiple builds, the 15 or 20 pcs option offers better per-unit value and ensures you have replacements on hand.

Anodizing is an electrochemical process that integrates color into the aluminum surface rather than coating it on top, so it is generally more durable than paint or plating under normal use. With hand-tightening use, the color should remain intact. Heavy abrasion, contact with harsh chemicals, or repeated tool-tightening can gradually wear the anodized layer over time.